Heat transfer liquid



July 2, 1935.

HEAT TRANSFER LIQUID.

Filed June 4, 1952 F. D; SNELL 2,007,007v

Patented July 2 1935 y UNITI-:o STATES 'PATENT kOFFICE 2,007,007 maar :n ANsFEnuQUm Foster Dee Snell, Brooklyn, N. Y. Application June 4, 1932, sei-nu No. 615,339

13 Claims.

1o be operated under conditions such that the coolv ing liquid is subjected to a wide range of temv peratures, such for example, as the 'engines-of airplanes and automobiles. For convenience of disclosure the invention will be more particularly described in this relation, but it willbe understood that the particular description is illustra'- tive and not intended as defining the limits of application of the invention.

In order to satisfy the requirements f use a 20 tures must be stable to resist decomposition and it should not evaporate unduly at operating temperatures. AIf itis subjected to low temperatures as when used in automobile and airplane engines, it must not freeze or so solidify as to prevent or seriously retard circulation when the engine is started after long exposure. Water as. a cooling medium though commonly used does not well satisfy these needs. Certainly it does not permit optimum working temperature. The anti-freeze liquids commonly used are troublesome in that they cause sluggish circulation and over-heating together with leakage at connections, and fre- 85 quently they do not give satisfactory protection against freezing. Furthermore, they are subject to the same objection as water in that they do not permit operation -of the engine at theoptim'um `working temperature. g

Thermodynamic considerations indicate that if the engine is operated at substantially higher temperatures thanvis usual practice, better mechanical emciency ls obtained.

The present invention has for an object to provide a heat exchangeliquid which will not corrode metals and will not become decomposed, polymerized or gummy after continued use.

Another object is to provide a liquid which will have a relatively low specific' heat. l

A further object is to provide, particularly for use in cooling systems such as those of automobile and aircraft engines in which the liquid is subject to a wide range of temperature, a non-freezing liquid which will flow freely at low temperaturcs and which will also have ahigh-boiling heat transfer liquid to be used at high temperaoperation of the engine at the thermodynamically factory price.

(Cl. 25a-5) point and permit operation of the engine at hightemperatures.

Another object is to provide a liquid which will show little change in viscosity over a wide temperature range. y

LA further object is to provide improved connections between the' radiator and the engine proper which will be sufllciently flexible to permit the unequal expansionand slight relative movement of the engine and radiator and connections which will not be impaired by-exposure' to the cooling liquid.

A still further Objectis to provide a complete. cooling system including a stable heat transfer 'liquid with a cooling radiator, an engine jacket and flexible connections within which the Vliquid can circulate without causng deterioration of the parts.

With the foregoing objects in view the invention provides a cooling liquid which operates effectively at high temperatures and as a par- `ticular species a liquid which is particularly suitable for use in automobiles and airplane engines under the conditions of use and improved exible connections for the engine and radiator which will withstand the deterioratingy effects of the cooling fluid. The liquid is also effective vfor use in maintaining a constant temperature as for example Vin catalytic baths and the like.

In the accompanying drawing the figure is a diagrammatic view conventionally illustrating a circulating system.

In accordance with the invention the preferred cooling liquid comprises partially or fully chlorinated benzene in which the chlorine is substituted for one or more hydrogen atoms of the benzene ring, or partially or wholly chlorinated naphthalene or diphenyl or a suitable mixture of these compounds. Of the chlorinated naphthalenes the alpha chloronaphthalene is probably the most practicable. It has a satisfactory range `between the melting point and boilingpoint and at present can be obtained commercially'at a satis- Y All of these liquids are stable at high temperatures. If only high temperatures are to be considered the compounds or mixtures having a high boiling point may be selected, but if the system is to be subjectto low temperatures the freezing point must also be considered. For a high temperature system, for example, hexachlorobenzene,

melting at 225 C., combined with a sufficient proportion of one of the lower chlorinated products or diphenyl to lower the melting point to the ex-` i tent desired provides an excellent heat exchange liquid. Depending upon the requirements. principally the desired temperature range, the proportions of the ingredients may vary widely. even a proportion of the order of 5% of one compound may sumciently lower the freezing point of the mixture to the desired range. Graphs may be drawn showing the melting points or boiling points of various proportions of the different ingredients; thus facilitating the selection of particular compounds for uses under Y particularly prescribed conditions.l

For a cooling system subject to a wide range of temperatures an effective composition may consist of trichlorobenzene to which is added alphachloronaphthalene or polychlorobenzcne in proportionsl to satisfy the conditions of Ordinarily for winter use in temperate climates a composition containing substantially one part by weight of trichlorobenzene and one part of alphachloronaphthalene and/or polychlorobenzene is satisfactory.

A composition containing equal parts by weight of polychlorobenzene (principally dichlorowith some trichloro-benzene) and alphachloronaphthalene has a freezing point of F. while one containing equal parts of trichlorobenzene and alphachloronaphthalene has a freezing point of -33 F. A composition containing equal parts by weight of trlchlorobenzene and polychlorobenzene has a freezing point of 3 F. Such composition of trichlorobenzene and'alphachloronaphthalene has been selected as a preferred composition, satisfying several practical requirements. It shows a viscosity variation of from about 85 secondsat 13 F. (Saybolt) to about 29 seconds at 210 F. As a matter of fact the viscosity varies relatively little between temperatures of 20 and 210 F., and although it falls oif quite rapidly at temperatures below 20 F. effective operation under operative conditions in an internal combustion engine is obtained.

The relatively slow flow of the cooling medium st flow temperatures is an advantage in that it permits the engine to'heat to operative temperature more quickly.

The rate of evaporation of the composition at engine temperature is very low. Tests made at a temperature of F. show an evaporation'from an open dish of about 55% after 26hou'rs as compared with an evaporation of over 56% of water after only 2 hours.

Corrosion tests on the metals commonly used in engine cooling systemsindicate either. no corrosion or such as is entirely negligible. In the tests made a small percentage of water was introduced into the composition for the reason that the presence of water in the hydrocarbon would tend to increasethe corrosion.

The composition is stable and does not produce s gummy residue upon continued use at high `temperatures. It is non-ble and non-explosive.

The specific heat is substantially less than that of water and will facilitate operation at higher temperatures.

'Ihe invention contemplates also the provision 'of improved exible connections between the engine and radiator which connection will withstand the action of the cooling liquid described. As a preferred connection a flexible metal tubing I -is employed between the engine 2 and the radi- -atm I, the tubing I beingof such construction that only metal is contacted bythe cooling liquid. A cooling-system in which the described cooling e of one of the lower chlorination products to lower the melting point (or the boiling point) to the desired temperature. The composition may then be used in a suitable apparatus suchas those of l known types in which mercury or other liquid is The foregoing particular description is illustrative merely and is not intended as defining the limits of the invention.

I claim:

l. A heat transfer liquid comprising a considerable proportion of trichlorobenzene and a substantial proportion of another relative nonvolatile liquid of the group consisting of-dlchlorobenzene, chlorinated naphthalene and diphenyl.

2. A heat transfer liquid comprising a considerable proportion of alphachloronaphthalene and a substantial proportion of another relatively nonvolatile liquid of the group consisting of chlorinated benzene and diphenyl.

3: A heat transfer liquid for usein the cooling systemof an internal combustion engine consistin gof a mixture of substantial proportions of at least two of the liquids, of the group consisting of the chlorinated benzenes, chlorinated naphthalenes and diphenyl.

4. A heat transfer liquid for use in the cooling system of an internal combustion engine'consist-f ing of a mixture of'substantlal proportions of at least two liquids of the group consisting of the chlorinated benzenes, the chlorinated naphthalenes and diphenyl combined in a proportion to reduce the meltingv point. .to a temperature below the temperatures to which the liquid is to be subjected in use. v

5. A heat transfer liquid for use in the cooling system of Van internal combustion engine consisting principally of a mixture of trichlorobenzene and a compound of the group consisting of alphachloronaphthalene and dichlorobenzene in a proportion sufficient to reduce the freezing point of the composition to a point below the temperature to which the composition is to be subjected in use.

l6. A heat .transfer liquid for' use in the cooling system of an internal combustion engine consisting principally of trichlorobenzene and alphachloronaphthalene in substantiallyv equal proportions.

7. A heat transfer liquid for use in the cooling system of an internal combustion engine consistserres, the chlorinated naphthalenes and diphenyl,

compounded in proportions to provide a melting 7 point at the predetermined temperature to be maintained.`

9. A liquid composition for use in a constant temperature bath comprising a mixture of liquids of the group consisting of the chlorinated ben- 75 sence, the chlorinated nephthelenes and diphenyl, compounded in proportions to provide a boiling point st th'e predetermined temperature to be 10. Aheet trsnsierliquidioruselntheoooling system oi en internal combustion engine comprising a mixture of tri-chloro-benzene and ulplis-v ehioro-naphthslene in e proportion suiilcient to reduce'the freezing point ci the mixture to e point below` the temperature to which the composition is to be subjected in use.

11. The-method oi cooling an internal combustion engine whichconsists in circulating s cooling medium theresbout, comprising as a principal ingredient trichlorobensene with 5% or more oi liquid fof the group consisting o! dichlorobenzene, alphechloronephthslene and diphenyl.l

12. The method oi cooling en internsl'combustion engine which consists in circulating s cooling medium thereabout, consisting principally of 'chlorinated benzene and chlorinated nsphthalene in proportions of the order o! l1 to 1. 13. A composition oi mutterhaving 's melting and having relatively slight viscosity change between these temperatures, consisting of a mixture of tri-chloro-benzene and another liquid oi the/ point below 0 C. and s boiling point above 100 C., 

